Rescuers struggling to save nine trapped Pennsylvania miners called on a host of high-tech gadgets to even the long odds against bringing the men back safely.

Before the diggers enter the wet and cold subterranean alcove in which the men are trapped, they will erect an airlock over the shaft to keep the area pressurized.

Because the area where the men are trapped is under high air pressure – similar to being under 40 feet of water – the men could suffer the bends if they are moved too quickly to an area of lower pressure.

To reduce that risk, nine decompression chambers, designed to battle the bends by slowing the air-pressure drop, have been brought to the mine-collapse site.

If any of the miners are able, they could climb into the capsule and be lifted to the surface. If no one boards the capsule, crews would have to decide to send rescuers down to retrieve them.